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Fetal Growth Restriction

Fetal Growth Restriction. Steven R. Allen, MD Scott & White Clinic TAMU-HSC. Educational Objectives. Review epidemiology and significance of fetal growth restriction (FGR) Know etiologies (= risk factors) Discuss screening strategies for FGR

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Fetal Growth Restriction

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  1. Fetal Growth Restriction Steven R. Allen, MD Scott & White Clinic TAMU-HSC

  2. Educational Objectives • Review epidemiology and significance of fetal growth restriction (FGR) • Know etiologies (= risk factors) • Discuss screening strategies for FGR • Evaluate the role for Doppler velocimetry in the diagnosis & mgmt of FGR • Develop treatment strategies for FGR

  3. Arbitrary threshold for “growth restriction” Weight Gest Age, weeks

  4. Variables affecting normal fetal growth* • Gender • Ethnicity • Number of fetuses • Altitude • Parental phenotype * generally not accounted for in growth curves

  5. Significance of fetal growth restriction (FGR) • 3-10% of newborns are “growth restricted” • associated morbidities • intrapartum FHR abnormalities • cord blood acidemia • cesarean delivery • neonatal hypoglycemia, hypothermia, and hyperbilirubinemia • 1/4 stillbirths are SGA

  6. FGR: neonatal morbidities27-32 wks gestation NS* % NS *RDS: not benefited by FGR AJ Perinat 2000;17:187

  7. Long term implications of FGR IQ • Outcome related to etiology - worse for aneuploidy, viral infxn • Catch-up growth common • Adult risks: HTN, hypercholesterolemia • Minimal reduction in IQ not predictive of academic achievement J Pediatr 2001;138:87

  8. Long term implications of FGR RR LBW vs heaviest Barker “thrifty phenotype” hypothesis • Fetus adapts to malnutrition • Cephalized blood flow • Metabolic programming beneficial to malnourished fetus is detrimental if adequate nutrition later available • Unknowns • Molecular basis • Relative roles of genetic & environmental factors Ozanne. Online review. 9/12/02. http://tem.trends.com

  9. Pathophysiology of FGR Cellular Hyperplasia Cellular Hypertrophy “symmetric” “asymmetric” 1 3 Trimester

  10. Etiology of FGR

  11. Etiology of FGR • “Symmetric”: • infection (<5%) • malformation • aneuploidy • low mat wt, wt gain • multiple gest • XR exposure

  12. Etiology of FGR • “Symmetric”: • tobacco • alcohol • substance abuse • teratogens

  13. Etiology of FGR “Constitutionally small” Placental mosaicism (up to 1/4) • “Asymmetric”: • HTN • renal dis • thrombophilia • hypoxia • anemia • advanced DM • malnutrition

  14. Prior IUGR as a predictor of subsequent stillbirth OR Swedish birth registry 1983-1997 Wks gest age of prior SGA birth Surkan. NEJM 2004;350;777-85

  15. Defects in “classic” model of FGR subsets • Many preterm fetuses with growth restriction secondary to maternal HTN have symmetric FGR • Many aneuploid fetuses have asymmetric growth (“head sparing”)

  16. Classification of FGR symmetric asymmetric

  17. Abnormal metabolic parametersseen in some populations with FGR • Most FGR fetuses have normal PO2 & PCO2 • Hct & Hgb usually normal, with high MCV and RDW (erythropoeisis/reticulocytosis) • Inconsistent hypoglycemia (& hypo-insulinemia) • Increased ratio of non-essential:essential AA • Hypertriglyceridemia • Thrombocytopenia

  18. Screening for FGR Etiologies = risk factors • Fetal • Maternal-fetal • Maternal • Idiopathic

  19. Screening for FGR Physical exam • Serial fundal height: between 18-30 weeks, FH(+/- 2-3 cm) = EGA in weeks • sensitivity for FGR = 40-67% • false pos rate = 50%

  20. Screening for FGR Ultrasonography • EFW • Abdominal circumference • Head:abdomen ratio • Serial measurements (rate of growth) • Amniotic fluid volume Anatomic survey indicated if FGR detected

  21. Screening for FGR Ultrasonography • 3rd TM AC sensitivity for FGR = 80% (no different than sensitivity of FH) • Reserve US for those pts at risk for FGR: • risk factors • S<D • prior SGA ACOG Prac Bull #12, 1/2000

  22. Doppler velocimetry Screening for FGR • sensitivity in Low Risk population: 15-30% • sensitivity in Hi Risk population: 75-95% • commonly associated with FGR, but not diagnositic • NOT uniquely helpful

  23. Doppler velocimetry: S/D ratio S/D = 3.1

  24. Doppler velocimetry Management of FGR • Umbilical artery: S/D ratio increases with placental resistance

  25. Umbilical artery in FGR

  26. Doppler velocimetry Management of FGR • Umbilical artery: S/D ratio increases with placental resistance • Middle cerebral artery: S/D ratio decreases with cephalization (“head sparing”)

  27. Middle cerebral artery in FGR

  28. Doppler velocimetry Management of FGR • Umbilical artery: S/D ratio increases with placental resistance • Middle cerebral artery: S/D ratio decreases with cephalization (“head sparing”) • Umbilical vein: becomes pulsatile with heart failure

  29. Umbilical vein in extreme FGR

  30. Doppler velocimetry Management of FGR • Umbilical artery: S/D ratio increases with placental resistance • Middle cerebral artery: S/D ratio decreases with cephalization (“head sparing”) • Umbilical vein: becomes pulsatile with heart failure • Ductus venosus: decreased forward velocity or reversal of “a” wave (atrial kick) • Changes typically occur in this sequence prompting a logical screening sequence

  31. Ductus venosus in extreme FGR “a” wave

  32. FGR example 1risk factor: tobacco Weight Gest Age, weeks Umb artery S/D nl

  33. FGR example 1: mgmt • d/c tobacco • serial US • biophysical testing and FACs • delivery plan?

  34. Umb art S/D predicts risk of neonatal morbidity % J US Med 2000;19:661

  35. FGR example 2risk factor: CHTN Weight Gest Age, weeks Umb artery S/D elevated

  36. FGR example 2: mgmt • MCA S/D ratio - minimally decreased; normal umb venous flow pattern • R/O PIH • serial US • biophysical testing and FACs • delivery plan?

  37. Interventions with UNproven efficacy • nutrient treatment • zinc supplementation • calcium supplementation • plasma volume expansion • oxygen • heparin • aspirin

  38. FGR example 3risk factor: AMA Weight Gest Age, weeks Oligohydramnios; umb art AED; MCA S/D low; umb vn pulsatile

  39. FGR example 3: mgmt • Continuous monitoring • Corticosteroids • Delivery after 24 hrs if stable

  40. Considerations for delivery • Non-reassuring acute fetal status • Cessation of growth over 2-4 wks • Oligohydramnios • “When extrauterine survival is likely in the presence of significantly abnormal antenatal testing” ACOG Prac Bull #12, 1/2000

  41. FGR: Summary Recommendations(Level A) • Umbilical artery velocimetry is useful to reduce perinatal death once FGR is suspected or diagnosed • No specific treatments (nutritional supplements, oxygen, heparin, ASA, volume expansion, or antihypertensive agents) effectively prevent or treat FGR ACOG Prac Bull #12, 1/2000

  42. FGR: Summary Recommendations(Level C) • Antepartum surveillance should be instituted when extrauterine survival is possible • No particular form of antenatal testing is superior • Screen low-risk pts for FGR using physical exam • US is appropriate screen for FGR in hi-risk pts ACOG Prac Bull #12, 1/2000

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